Best Open-Source AI Agent Frameworks in Python 2026: 10 Compared with Stars

Choosing a Python agent framework in 2026? These 10 open-source options with real star counts make it easier.

## Best Open-Source AI Agent Frameworks in Python 2026 All star counts below come from the ainomam GitHub star tracker snapshot dated 2026-07-31. ### The rankings 1. **LangGraph** - 38,573 stars (part of LangChain 143,097). Stateful, graph-based agent orchestration. The 2026 default for production. 2. **AutoGen** - 60,129 stars. Microsoft multi-agent conversation framework; now with AutoGen Studio for visual building. 3. **CrewAI** - 56,432 stars. Role-based crews; the friendliest onboarding in the ecosystem. 4. **LlamaIndex** - 51,260 stars. Agents deeply integrated with RAG pipelines and 40+ data connectors. 5. **Phidata** - 41,526 stars. Agent platform with built-in UI, monitoring, and tool integrations. 6. **Haystack** - 26,073 stars. Production-oriented agent orchestration with strong evaluation tooling. 7. **Semantic Kernel** - 28,396 stars. Microsoft cross-language framework (C#/Python). 8. **TaskWeaver** - 6,176 stars. Code-first agent framework; good for data workflows. 9. **Eliza** - 18,856 stars. Agent framework with a focus on social and autonomous agents. 10. **AgentVerse** - 5,091 stars. Research-focused multi-agent simulation framework. ### How to choose - **Production SaaS**: LangGraph - **Quick prototype**: CrewAI - **RAG-heavy apps**: LlamaIndex - **Multi-agent research**: AutoGen or AgentVerse - **Enterprise, polyglot teams**: Semantic Kernel ### Minimum viable agent in CrewAI [python] from crewai import Agent, Task, Crew researcher = Agent(role="Researcher", goal="Find facts", backstory="A careful analyst") task = Task(description="Summarize MCP adoption in 2026", agent=researcher) crew = Crew(agents=[researcher], tasks=[task]) print(crew.kickoff()) [/python] ### FAQ **Which framework has the most stars?** AutoGen (60,129), followed by CrewAI (56,432). **Can I combine frameworks?** Yes, many teams use LlamaIndex for retrieval inside a LangGraph orchestration layer.